The Jaguar Codex was an ancient book, hidden in a vault in a pyramid near Lucasio, Mexico. The codex was sought by the Nazis, who believed that the incantations contained in it would allow them to summon the spirit of Kukulkan to lead them to victory in Europe. Indiana Jones foiled their plan by recovering the book first in the course of his adventures in Mexico in the 1930s.
The Codex was kept under a small pyramid, in a large hall filled with Guardian Statues that would come to life and attack anyone who touches them. Jones had to destroy all 8 statues in order to open the vault and obtain the artifact.